On HED models 75, 100, 125 and 150, mounting nuts
are furnished at the balance point (two positions only).
On HED models 200, 250 and 300, mounting nuts are
furnished at each corner of the unit. Mounting nuts will
accommodate 3/8" x 16 threaded rods.
1 − Cut threaded rods to desired length and slide a
3/8" nut onto the rod.
2 − Slide a flat washer onto the threaded rod AFTER
the nut (7/16" inside diameter X 1" outside
diameter X 1/16" thick washer).
3 − Screw the rods (two or four) into the mounting
nuts on the unit.
4 − Tighten nuts to secure unit to rods.
Combustion and Ventilation Air
Adequate facilities for supplying air for combustion and
ventilation must be provided in accordance with the
current edition of ANSI Z223.1, section 5.3, and
CSA−B149 installation compliance codes, or applicable
provisions of local building codes.
All gas-fired appliances require air to be used for the
combustion process. In many buildings today, there is a
negative indoor air pressure caused by exhaust fans, etc.
If sufficient quantities of combustion air are not
available, the heater or another appliance will operate
in an inefficient manner, resulting in incomplete
combustion which can result in the production of
excessive carbon monoxide.
If indoor air is to be used for combustion, it must be
free of the following substances or the life of the heat
exchanger will be adversely affected: chlorine, carbon
tetrachloride, cleaning solvent, halogen refrigerants,
acids, cements and glues, printing inks, fluorides, paint
removers, varnishes, or any other corrosives.
Rotation of Combustion Air Inducer
(HED−75, −100, −125 and −150 Only)
The combustion air inducer on HED models −75, −100,
−125 and −150 may be rotated 90° either to the left or
right of the original vertical position in order to better
suit the application.
NOTE
− It is not permissible to rotate the combustion
air inducer on HED models −200, −250 and −300.
Rotate the combustion air inducer assembly as follows:
1 − Remove the heater from the carton. Decide the best
duct heater orientation. The vent can be installed in
one of three discharge positions: up, left, or right.
2 − If the inducer is to be rotated, follow the
instructions in this section; otherwise, refer to
instructions under Venting" section.
3 − Before making an electrical or gas connections,
remove the securing screws on the flue
box/combustion air inducer. See figure 2.
FLUE BOX AND
COMBUSTION AIR INDUCER ASSEMBLY
FLUE BOX GASKET
FLUE BOX
VEST PANEL
COMBUSTION AIR INDUCER GASKET
COMBUSTION AIR INDUCER
FIGURE 2
4 − Remove the flue box/combustion air inducer
assembly, ensuring that the gasket is not
damaged. If the gasket is damaged, replace it.
5 − Use a 1/4" socket to remove the three screws which
secure the combustion air inducer to the flue box.
Remove the inducer and gasket from the flue box
ensuring that the gasket is not damaged. If the
gasket is damaged, replace it.
6 − Use the template provided in the back of this
manual to mark new hole locations. Use a 7/32"
drill bit to drill holes in flue box.
7 − Place the gasket between the combustion air
inducer and the flue box. Rotate both the inducer
and the gasket 90° to the desired position.
Reinsert and tighten the three inducer securing
screws (#8−16 X 1/2" HWHSMS).
8 − Place the gasket between the flue box and the vest
panel. Position the flue box/combustion air inducer
assembly on the vest panel. Fasten the flue box to
the vest panel using the flue box securing screws
(#10−16 X 5/8" HWHSMS) and a 5/16" driver.
9 − The duct heater is now ready for installation as
described in the Venting section.
Do not use the gas manifold pipe to lift unit. Any
excessive upward or downward force on the
manifold pipe and bracket assembly can cause the
ignition burner and igniter to become misaligned.
IMPORTANT
Insufficient combustion air can cause headaches,
nausea, dizziness, asphyxiation or death.
CAUTION
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